Truing device for grinding wheel with rotating cup-shaped truing cutter

ABSTRACT

A cup-shaped truing cutter device is provided which precisely forms various selective contours, such as a flat, concave, or convex contour, on the peripheral surface of a grinding wheel according to the radial inclination of the axis of the device in the vertical dividing plane passing through the grinding wheel normal to the axis of the wheel. The cup-shaped truing cutter is tangentially fed to thereby precisely true the peripheral surface of any grinding wheel by a constant crowning amount without relation to the grinding wheel diameter under the constant inclination of the axis thereof.

1451 July25, 1972 References Cited [54] TRUING DEVICE FOR GRINDING 3,481,319 12/1969 Boyd....................................125/11R ....51/289R X L m s T. u N m E u T m A m P m S u m 1 mm D C m I 7 mm W 7 2 6 2 R m HT w G R N H] U IR WT D ME EP m Ws [72] Inventor: Makoto Kikuchi, Kariya, Japan 3,056,243 10/1962 Flanders... 3,581,730 6/1971 Boyd.................................125/1l CD [73l Assignee: Toyoda Machine Works, Limited, Kariyashi, Japan Primary Examiner-Harold D. Whitehead Attorney-Oblon, Fisher & Spivak [22] Filed: Feb. 5,1971

[21] App1.No.:

[] Foreign Application Priority Data Feb. 11, 1970 1 1733 convex contour, on the peripheral surface of a grinding wheel according to the radial inclination of the axis of the device in 52 us. Cl. co, 51/131 51/289 R the Vertical dividing Plane Passing s the grinding Wheel normal to the axis of the wheel. The cup-shaped truing cutter is tangentially fed to thereby precisely true the peripheral sur- [51] /11 R, 11CD;51/131, 124L,

51 289 R face of any grinding wheel by a constant crowning amount without relation to the grinding wheel diameter under the constant inclination of the axis thereof.

[58] Field of Search 9 Claims, 9 Drawing Figures Patented July 25,1972 BEST AVAIL L W 3,678,915

SShuts-Shoet 5 Fig-4 Pmmd J ly 25,1972 BBSTAVAILABLE' COPY 3.678.9

5 Shuts-Shut 4 Patentod July 25, 1972 BE T AVAIL BLE COPY 5 Sheets-Shut 5 TRUING DEVICE FOR GRINDING WHEEL WITH ROTATING CUP-SHAPED TRUING CUTTER BACKGROUND OF THE INVENTION This invention relates generally to grinding wheel truing, or precise dressing, and more particularly concerns a truing device which precisely forms a selected one of various contours, such as a flat, a concave, and a convex contour, on the peripheral surface of a grinding wheel according to the inclination of the truing cutter axis relative, to a radial direction of the grinding wheel.

In truing operations, the peripheral contour of a grinding wheel is usually formed or trued by the truing device in accordance with the peripheral contour that must be applied to the ground surface of a workpiece.

Heretofore, copying type and plunge cut dressing systems have been generally employed in performing the aforementioned truing operations. In the copying type system, a singlepoint diamond tool is moved in accordance with the contour of a template, and thus the grinding wheel can only be dressed in the contour provided by the particular template. If it becomes necessary to dress the grinding wheel with a different contour, however, an exchange of templates is required. Similarly, in the plunge cut dressing system, many expensive diamond rolls must be provided to be exchanged in accordance with the various contours required on the grinding wheel surface. 1

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an improved truing device which precisely forms various selective contours, such as flat, concave, and convex contours, on the peripheral surface of a grinding wheel without the use of different templates or like guiding surfaces.

It is another object of the present invention to provide a new and improved truing device having a single cutting surface which precisely trues the peripheral surface of any grinding wheel by a constant crowning amount without relation to the grinding wheel diameter under a constant inclination of the truing cutter axis.

According to the present invention, the foregoing and other objects are attained by a'truing device for a grinding wheel which comprises a cup-shaped truing cutter having a cylindrical portion, the end of which is coated with diamonds or other abrasive particles, a motor for rotating the truing cutter, an adjustor for adjustably inclining the rotating cutter axis, which is located on a vertical dividing plane passing through the grinding wheel normal to the axis thereof, relative to a given radial direction of the wheel, and means for feeding the truing cutter toward the grinding wheel surface to form a preselected peripheral contour thereon corresponding to the adjusted inclination of the truing cutter axis. Furthermore, the feeding means preferably comprises two separate feed devices, one of which feeds the truing cutter in a predetermined direction tangential to the grinding wheel peripheral surface for truing the peripheral surface of any grinding wheel by a constant crowning amount without relation to the grinding wheel diameter under a constant inclination of the cutter axis, and the other of which feeds the truing cutter by a dressed amount along aradial direction of the grinding wheel perpendicular to the predetermined tangential direction.

DESCRIPTION OF THE DRAWINGS Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detailed description of a preferred-embodiment, when considered in connection with the accompanying drawings, in which like reference numerals are used throughout to designate like or corresponding parts, and wherein:

FIG. 1 is a front view showing a grinding wheel truing device constructed according to the present invention;

FIG. 2 is a top plan view of the device shown in FIG. I;

wheel to a concave surface;

FIG. 8 is a schematic view showing a truing movement of the cup-shaped truing cutter in the course of truing a grinding wheel to a convex surface; and

FIGS. 9A and 9B are schematic views showing the relationship between the crowned amount of a grinding wheel and the feed of the cup-shaped truing cutter of this invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, and more particularly to FIGS. 1 and 2, a grinding wheel 2 is rotatably mounted on a wheel slide 1, on which a pedestal 3 is securely mounted to slidably support an elongate vertically oriented slide 4 in parallel with a line YY drawn through the center of the grinding wheel 2. The slide 4 supports a guide plate 5 extending both right and left of the 'top surface thereof on which a carriage 6 is slidably mounted for movement in a horizontal direction perpendicular to the vertical sliding direction of the slide 4. A cylinder 7 is formed in the guide plate 5 for slidably receiving a piston 8 having a piston rod 9 connected thereto and the piston rod 9 is secured to one end of the carriage 6.

The cylinder 7 forms two separate chambers 7a and 7b which are separated by the piston 8. Projecting into the cylinder chamber 7b is an adjusting knob 10 which threadably engages the end of the guide plate 5 for adjusting the stroke of the piston 8.

On the other end of the carriage 6 is fixed a bracket 11 which slidably supports a cutter head 12 for movement parallel with that of the slide 4. The cutter head 12 is threadably engaged with a feed screw 13, on the end of which a hand wheel 14 rotatably mounted in the top of the bracket 11 is secured for adjustably positioning the cutter head 12 radially relative to the peripheral surface of the grinding wheel 2.

A swivel base I5 is rotatably mounted about a pivot I6 on the lower edge of the cutter head 12. An upper projection 17 of the swivel base 15 is fixedly interposed between a pair of adjusting bolts 18 which serve to adjustably rotate the swivel base 15 to an arbitrary or selective swivel position and a plurality of elongated slots 20, shown as being four in number, are formed in the swivel base 15 for permitting the swivel base 15 to adjustably rotate about the pivot 16. Clamp bolts 19 through the elongated slots 20 threadably engage the cutter head 12 for securely clamping the swivel base IS in the selected swivel position on the cutter head 12.

Mounted on the swivel base 15 for rotating a diamond truing cutter 22 is an electric motor 47. The truing cutter 22 is cup-shaped and is keyed to and securely held by a nut 23 on a shaft 21 driven by the motor 47, the axis of which lies in a vertical dividing plane passing through the center of the grinding wheel width normal to the wheel axis. The cup-shaped diamond truing cutter 22 has a cylindrical end portion 24 with a semicircular sectional contour which is adapted to face the peripheral surface of the grinding wheel 2. The edge of the cylindrical portion 24 is coated with diamond particles attached in a suitable manner well known to those skilled in the art. Also, the center 0 of the semicircular sectional profile is positioned on the axial line of pivot 16. In other words, the axial line of pivot 16 is located'on a tangential line of the circular center line of the semicircular sectional profile. Therefore, the diamond truing cutter 22 may be inclined about a tangential line of the circular center line of the semicircular sectional profile since the swivel base can be swiveled about the pivot 16 underthe operation of adjusting bolts 18.

A feed mechanism, shown in FIGS. 4 and 5, is provided for moving the wheel slide 1, and consequently the grinding wheel 2 supported thereon, toward and from a workpiece, not shown. The feed mechanism also serves as a compensating device which moves the wheel slide 1 and the slide 4 affixed thereto for the purpose of providing compensation for the reduction in radius of the grinding wheel 2 due to the wear thereof and the truing operation performed thereon.

A sleeve 36 is mounted on the lower side of the wheel slide 1 and is prevented from rotating within the wheel slide 1 while being permitted to move in an axial direction only therewith by a key engagement provided therewith.

A feed screw is threadably engaged with the sleeve 36 at one end thereof and extends into a gear box 27 mounted on the rear of wheel slide 1 to be rotatably supported at the other end thereof in a bushing 28. The bushing 28 is fixedly mounted in the gear' box 27 and also rotatably supports a pinion 29 which meshingly engages a rack formed on a piston rod 32. The piston 31, FIG. 5, having the piston rod 32 thereon is slidably received in a cylinder 30 for rendering a rotating motion to the pinion 29 upon axial movement thereof. To the pinion 29 is keyed a swivel arm 33, at the end of which a ratchet pawl 34 is pivoted in such a manner that it engages with a ratchet wheel secured to the end of feed screw 25 outside the bushing 28 and pinion 29. The cylinder 30 includes a chamber 30a on one side of the piston 31 and is closed at its other end by a cap having an inner recess 30b in which there is disposed a spring for normally urging the piston 31 in the direction of the chamber 30a. Thereby, the feed screw 25 is adapted to be rotated in only one direction by the pinion 29, namely in a counterclockwise direction, as observed in FIG. 5, upon movement of the piston rod 32 toward the right. When the piston rod 32 is returned to the left under the influence of the spring in chamber 30b, the rack thereon rotates the pinion in a clockwise direction, whereby the ratchet pawl 34 moves in the same direction over the ratchet wheel 35 without causing the wheel to rotate, and the device is thus prepared for the next truing operation.

Rotatably mounted in a base 50 is another feed screw 26 which is threadably engaged with a movable nut 37. At one end of the feed screw 26 there is provided in the gear box 27 a hydraulic actuator 52 which normally urges the feed screw 26 in an axial direction to the left, as shown in FIG. 4, and simultaneously urges the gear box 27, wheel slide 1 to which it is affixed, and the sleeve 36 and feed screw 25 disposed therein to the right, or in an opposite direction relative to the feed screw 26 and the movable nut 37. The nut 37 is slidably mounted on the base 50 and may be engaged with a downwardly projecting U-shaped extension 51 of the sleeve 36 which straddles the feed screw 26. Thus, the extension 51 of the sleeve 36 is always maintained in contacting engagement with the movable nut 37.

Between the nut 37 and the hydraulic actuator 52, there is disposed another hydraulic actuator, illustrated schematically and in section, which is effective upon actuation thereof to advance the wheel slide 1 at a rapid speed toward the workpiece through the nut 37', the sleeve 36 engaged therewith, and the feed screw 25, the latter through its engagement with a stop 38 on the wheel slide 1 causing the same to be moved therewith.

A motor, not shown, is operatively connected to the feed screw 26 for rotating the screw 26, whereupon the movable nut 37 may be moved back and forth so that the wheel slide 1 is moved slowly toward or from the workpiece to complete the grinding operation on the workpiece by the grinding wheel 2, the nut 37 and the sleeve 36 always being keptin engagement by means of the hydraulic actuator 52. On the rear of sleeve 36 there is formed a rack 39 which is meshed with a pinion 41 keyed to a shaft 40 rotatably mounted in the wheel slide 1. The pinion 41 is rotated in a clockwise direction by this leftward movement of the sleeve 36.

Referring now to FIG. 3, a gear 42 is shown being keyed to the end of the shaft 40 which is meshingly engaged with a vertical rack 43 secured to the slide 4, whereby the slide 4 is adapted to be moved vertically in accordance with the feed amount of the sleeve 36 through the rotation of the feed screw 25, in this case being moved downwardly for lowering the truing cutter 22 in the manner to be set forth hereinbelow. A cylinder 44 is formed in the vertical carriage 4 for slidably receiving a piston 45 which divides the cylinder into two chambers 44a and 44b, and the piston rod 46 of piston 45 is secured to the pedestal 3. Fluid under pressure is supplied to the upper chamber 44a of the cylinder 44 to eliminate backlash of the gearing.

The operation of the grinding wheel truing device will now be described. If the peripheral contour of the grinding wheel2 is to be formed as a straight line, the swivel base 15 is adjustably rotated about the pivot 16 by the adjusting bolts 18 after first releasing the clamp bolts 19 so that the axis of the diamond truing cutter 22 may be disposed in parallel relation with the line YY, as shown in FIG. 6. After the parallel relationship between the truing cutter axis and line YY is obtained, the swivel plate 15 is clamped in place by the clamp bolts 19. Thus, the diamond truing cutter 22 is located .in a position D shown by the phantom lines in FIG. 6. Then, the electric motor 47 is energized to rotate the diamond truing cutter 22 at a high speed. The diamond truing cutter 22 which is supported on the slide 4 is then downwardly fed from the position D to the position E, as shown in FIG. 6, by the ratchet device 34,35 through the aforedescribed gearing including feed screw 25, rack 39, pinion 41, gear 42 and rack 43 in FIG. 3. Thereafter, when the fluid under pressure is applied to the right chamber 7b of cylinder 7, the diamond truing cutter 22 is advanced in the tangential direction relative to the grinding wheel 2 to the position shown in real or solid line form in FIG. 6, whereby a straight line is formed on the peripheral profile of the wheel 2.

In case the peripheral contour of the grinding wheel 2 is to be formed as a concaveline, the swivel base 15 is adjustably rotated about the pivot 16 by the adjusting bolts 18 after releasing clamp bolts 19 so that the truing cutter axis may be inclined by an angle A0,, relative to the line YY. After the truing cutter axis has been inclined by this predetermined angle, the swivel base 15 is clamped tightly in position by the clamp bolts 19. Thus, the diamond truing cutter 22 is located in the position D shown by the phantom line in FIG. 7. Then, the electric motor 47 is energized to rotate the diamond truing cutter 22 at a given highcutting speed. The diamond cutter 22 is downwardly fed from the position D to the position E,'as shown in FIG. 7, by the ratchet device 34, 35 through the gearing hereinbefore identified, including feed screw 25, rack 39, pinion 41, gear 42 and rack 43 in FIG. 3. Thereafter, when the fluid under pressure is applied to the right chamber 7b of cylinder 7, the diamond cutter 22 is advanced in the tangential direction relative to the grinding wheel 2 to the real line position shown in FIG. 7, thereby to form the peripheral contour of the grinding wheel as a concave line.

Finally, in the case where the peripheral profile of the grinding wheel 2 is to be formed as a convex line, the swivel base 15 is adjustably rotated about the pivot 16 by the adjusting bolts 18 after releasing clamp bolts 19 in the same manner hereinbefore described so that the truing cutter axis may be inclined by an angle A0 relative to the line-YY, as shown in FIG. 8. After the truing cutter axis has been inclined to this predetermined position, the swivel plate 15 is clamped by the clamp bolts 19. Thus, the diamond cutter 22 is located in the position D shown in phantom in FIG. 8. Again, the electric motor 47 is energized to rotate the diamond cutter 22 at a high speed. The diamond cutter 22 is downwardly fed from the positionv D to position E, as shown in FIG. 8, and then is advanced in the tangential direction relative to the grinding wheel 2 to the position shown in reel or solid line, whereby the peripheral contour of the wheel is formed as a convex line.

Referring now to FIG. 9, there is described below the relationship existing between the feed amount of the diamond truing cutter 22 and the crowning of a grinding wheel 2 formed by the diamond truing cutter 22. Point A shows the forward end of cup-shaped diamond cutter 22 which is inclined relative to the line YY, in the manner shown in FIG. 7 for making a concave peripheral surface on the grinding wheel 2, while point P is an intersection between the sides of the peripheral edge surface of the grinding wheel 2 and the cylindrical portion edge of the cup-shaped diamond cutter 22. The position of point P is defined by the width of the grinding wheel 2 and the diameter of the diamond cutter 22 and is located apart from the point A by a constant distance PA without relation to the diameter of grinding wheel 2 and the feed amount of diamond cutter 22. When the diamond truing cutter 22 is fed along the line YY to cut away the grinding wheel 2 having a diameter R, by a depth L, the center of the peripheral surface of the grinding wheel 2 if formed into a concave portion having a radius R while the sides of the peripheral edge surface of the grinding wheel 2 each have a radius R as shown in FIG. 9A. Therefore, the center of grinding wheel 2 is dressed deeper by the desired crowning amount L,, which is the difference between the radii R and R Furthermore, as shown in FIG. 98, when the diamond truing cutter 22 is fed along the line YY to cut away a grinding wheel 2a having a different radius r by the same depth L, the center of the grinding wheel 2a is dressed into radius r while the sides of the peripheral edge surface of the grinding wheel 2a is formed into a radius r whereby a crowning amount L is obtained which is the difference between the radii r and r Comparing the crowning amount L with L,, as shown in FIG. 9, an error AL of the crowning amounts, that is L L appears due to the differential between the radii R and r, of the grinding wheels 2 and 2a, even though the grinding wheels 2 and 2a are cut away by the same amount L. This crowning error AL is eliminated by the feed motion of diamond truing cutter 22 in the tangential direction perpendicular to the line YY, since the point P is shifted leftwardly in accordance with the tangential feed motion of diamond truing cutter 22. Thus, a constant crowning amount L is provided on the peripheral surface of any grinding wheel regardless of the grinding wheel diameter.

Although a specific embodiment of the present invention has been shown and described, it is obvious that many modifications and variations thereof are possible in light of the teachings incorporated herein. It is to be understood, therefore, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by letters patent of the United States is:

l. A truing device for a grinding wheel, comprising:

a wheel slide for rotatably supporting said grinding wheel;

a carriage slidably mounted on said wheel slide;

an actuator mounted on said wheel slide for reciprocably moving said carriage in a tangential direction of said grinding wheel;

a cutter head slidably mounted on said carriage;

means for feeding said cutter head in a direction perpendicular to said tangential direction;

a swivel base pivotably mounted on said cutter head;

a cup-shaped truing cutter having a cylindrical portion, the end of said cylindrical portion being coated with abrasive particles;

a motor mounted on said swivel base for rotating said truing cutter; and

an adjustor mounted on said cutter head for adjustably inclining the axis of said tming cutter, relative to said direction perpendicular to said tangential direction, said axis being located on a vertical dividing plane passing through said grinding wheel normal to the axis of said rinding wheel. 2% truing device according to claim 1, in which said cylin- 5 drical portion has a semicircular sectional contour on the end thereof, said swivel base being rotatable about a tangential line of the circular center line of said semicircular sectional contour.

3. A truing device according to claim 2, in which said ad- 0 justor comprises a projection on said swivel base; and

a pair of adjusting bolts threadably engaging said cutter head and engaging said projection thereon for adjustably inclining said swivel base about said tangential line.

4. A truing device for a grinding wheel, comprising:

means for rotatably supporting said grinding wheel;

a cupshaped truing cutter having an abrasive cyclindrical portion;

means for supporting said truing cutter with the axis thereof being disposed in a vertical dividing plane passing through said grinding wheel normal to the axis of said grinding wheel;

means for reciprocably moving said truing cutter relative to said cutter supporting means along a line substantially tangential with respect to said grinding wheel;

means for moving said cutter supporting means in a path perpendicular to said tangential line of movement of said truing cutter moving means; and

means for adjustably inclining the axis of said truing cutter relative to a line parallel with said perpendicular path.

5. A truing device according to claim 4, wherein said truing cutter moving means comprises:

a guide plate fixedly mounted on said cutter supporting means;

a carriage slidably mounted on said guide plate; and

an actuator for sliding said carriage in said guide plate.

6. A truing device according to claim 5, wherein said truing cutter axis adjusting means comprises:

a cutter head slidably secured to said carriage for movement in a line parallel with said perpendicular path;

a swivel base pivotally mounted on said cutter head;

a motor mounted on said swivel base for rotating said truing cutter; and

an adjusting device for pivotally moving said swivel base on said cutter head and securably fixing the swivel base in its adjusted position.

7. A truing device according to claim 6, further comprising:

a feed screw threadably engaging said cutter head for sliding said cutter head in said carriage; and

a hand wheel rotatably mounted on said carriage for rotating said feed screw.

8. A truing device according to claim 4, in which said cylindrical portion of said truing cutter has a semicircular sectional contour on the end thereof, said swivel base being rotated by said adjustor about a tangential line of the circular center line of said semicircular sectional contour.

9. A truing device according to claim 7, wherein said means for moving said cutter supporting means in a path perpendicular to said tangential line of movement of said truing cutter moving means comprises:

a feed screw rotatably mounted in said cutter supporting I 

1. A truing device for a grinding wheel, comprising: a wheel slide for rotatably supporting said grinding wheel; a carriage slidably mounted on said wheel slide; an actuator mounted on said wheel slide for reciprocably moving said carriage in a tangential direction of said grinding wheel; a cutter head slidably mounted on said carriage; means for feeding said cutter head in a direction perpendicular to said tangential direction; a swivel base pivotably mounted on said cutter head; a cup-shaped truing cutter having a cylindrical portion, the end of said cylindrical portion being coated with abrasive particles; a motor mounted on said swivel base for rotating said truing cutter; and an adjustor mounted on said cutter head for adjustably inclining the axis of said truing cutter, relative to said direction perpendicular to said tangential direction, said axis being located on a vertical dividing plane passing through said grinding wheel normal to the axis of said grinding wheel.
 2. A truing device according to claim 1, in which said cylindrical portion has a semicircular sectional contour on the end thereof, said swivel base being rotatable about a tangential line of the circular center line of said semicircular sectional contour.
 3. A truing device according to claim 2, in which said adjustor comprises a projection on said swivel base; and a pair of adjusting bolts threadably engaging said cutter head and engaging said projection thereon for adjustably inclining said swivel base about said tangential line.
 4. A truing device for a grinding wheel, comprising: means for rotatably supporting said grinding wheel; a cup-shaped truing cutter having an abrasive cyclindrical portion; means for supporting said truing cutter with the axis thereof being disposed in a vertical dividing plane passing through said grinding wheel normal to the axis of said grinding wheel; means for reciprocably moving said truing cutter relative to said cutter supporting means along a line substantially tangential with respect to said grinding wheel; means for moving said cutter supporting means in a path perpendicular to said tangential line of movement of said truing cutter moving means; and means for adjustably inclining the axis of said truing cutter relative to a line parallel with said perpendicular path.
 5. A truing device according to claim 4, wherein said truing cutter moving means comprises: a guide plate fixedly mounted on said cutter supporting means; a carriage slidably mounted on said guide plate; and an actuator for sliding said carriage in said guide plate.
 6. A truing device according to claim 5, wherein said truing cutter axis adjusting means comprises: a cutter head slidably secured to said carriage for movement in a line parallel with said perpendicular path; a swivel base pivotally mounted on said cutter head; a motor mounted on said swivel base for rotating said truing cutter; anD an adjusting device for pivotally moving said swivel base on said cutter head and securably fixing the swivel base in its adjusted position.
 7. A truing device according to claim 6, further comprising: a feed screw threadably engaging said cutter head for sliding said cutter head in said carriage; and a hand wheel rotatably mounted on said carriage for rotating said feed screw.
 8. A truing device according to claim 4, in which said cylindrical portion of said truing cutter has a semicircular sectional contour on the end thereof, said swivel base being rotated by said adjustor about a tangential line of the circular center line of said semicircular sectional contour.
 9. A truing device according to claim 7, wherein said means for moving said cutter supporting means in a path perpendicular to said tangential line of movement of said truing cutter moving means comprises: a feed screw rotatably mounted in said cutter supporting means; means for rotating said feed screw; a sleeve threadably engaged with said feed screw and axially movable thereon; a rack on said sleeve; and means cooperable with said rack and responsive to movement thereof for causing said cutter supporting means to move in said perpendicular path. 